1. Field of the Invention
The present invention relates to self-venting valves, and more particularly to a self-venting valve for draining water from fuel filter assemblies.
2. Description of the Prior Art
Self-venting liquid drain valves have been known in the art for many years. Specifically, various assemblies have been made to provide fluid drainage from a vessel while providing a separate inlet for gas, such as air, to replace the fluid being drained. For example, in fuel/water separators used in diesel engines, water must be periodically drained using a valve assembly adapted to feed air into a separator while the water is being drained. The prior art devices have accomplished this by providing separate air and liquid passages formed through a portion of the valve assembly member.
A problem that occurs with fluid filter assemblies, particularly useful for diesel engines and gasoline marine engines, is facilitating the removal of contaminants from the filter assembly. These contaminants include water and particulate matter that tend to settle at the bottom of housings used to retain filter elements. In order to remove the water and particulate matter suspended in the water, drain valves are frequently positioned at the bottom of housings used to retain filter elements. If a simple drain cock is utilized for the valve, the drainage may not be complete or may not occur at all because a partial vacuum is created in the filter housing upon initiating drainage. The partial vacuum prevents water from flowing through the open valve.
In order to facilitate drainage by breaking the partial vacuum, drainage valves in fuel filters are vented. It is necessary to close the vent hole when the valves are closed so that fluid within the fluid filter does not flow out through the vent hole. In prior art arrangements there is the possibility of vent holes becoming blocked by particulate debris suspended in the fuel or water at the bottom of the housing. This is because the end of the vent tube, which opens within the housing, is left continuously open so that over time particles can accumulate in the vent tube.
Furthermore, currently used drain valves are made of multiple parts that makes them expensive in manufacturing and laborious and difficult to assemble.
The present invention provides a new and improved self-venting drain valve for filter assemblies and the like, which self-venting valve is reliable and is configured for ease of assembly and operation. The self-venting drain valve is provided for selectively permitting and preventing draining of contaminant liquid, such as water, from a housing of the filter assembly, such as a fuel filter assembly.
The self-venting drain valve in accordance with the preferred embodiment of the present invention includes a one-piece unitary valve body slidably received within a valve retaining bore in the filter housing between a closed position preventing draining of contaminant liquid and an open position permitting draining of contaminant liquid. The homogenously formed one-piece unitary valve body comprises a valve stem portion positioned in the valve receiving bore within the filter housing, and a valve knob portion disposed at a lower portion of the valve stem portion and positioned outside the filter housing.
The valve stem portion includes a substantially tubular wall member defining an internal passageway provided with at least one drain hole through which water is drained from the filter housing and the internal passageway, at least one cantilever snap arm formed in an upper end of the tubular wall member and at least one air vent opening therethrough defined by an axially extending space provided between the tubular wall member and the snap arm and through which ambient air can enter a filter housing through the internal passageway. Both the drain hole and the air vent opening are adapted to fluidly communicate the internal passageway to an ambient air.
The air vent opening is formed through an upper end of the wall member and is open to a top edge thereof, while the drain hole is formed through the lower portion of the wall member. Thus, the entry of air into the housing of the filter assembly as allowed by the air vent openings is above the drain holes in order to facilitate drainage of the filter housing as proper siphoning of water has been found to be assisted. It has been also found that the drain holes of the water outlet should open slightly before the air vent openings of the air inlet opens to provide the proper flow sequencing. This function is achieved by locating the air vent openings well above the drain holes into the wall member of the valve stem portion.
Preferably, the valve body comprises two opposite drain holes and two opposite cantilever snap arms and, respectively, two opposite air vent openings.
Moreover, the lower portion of the wall member is provided with external threads which threadedly mate and are received within the internally threaded base of the filter housing. The external threads engage the internally threaded base when the drain valve is in the closed position. When the drain valve is in the open position, the snap arms formed at the upper end of the wall member engages the threaded base of the filter housing to secure open the drain valve.
The valve knob portion is adapted to facilitate manual operation of the drain valve and to assist in draining water from the filter housing. The valve knob portion includes a substantially annular groove facing the valve stem portion and defining a drain reservoir, and a drain spout forming a drain passageway through which the water drains. The liquid drains from the filter housing through the internal passageway and the drain holes, then into the drain reservoir in the valve knob portion, and exits the valve through the drain spout.
Preferably, the valve body of the self-venting drain valve including the tubular stem portion and the knob portion is homogenously formed as a one-piece unitary member and is made of a plastic material by an injection molding process.
Therefore, the one-piece self-venting drain valve in accordance with the present invention provides a simple self-venting liquid drain valve permitting liquid such as water to drain while gas such as ambient air enters the vessel being drained to facilitate drainage, even when the filter housing is subjected to a vacuum. The self-venting drain valve of the present invention is relatively simple and inexpensive to manufacture because of the simplicity of its design that is a significant improvement over prior art valves.
Upon further study of the specification and appended claims, further features and advantages of this invention will become apparent to those skilled in the art.